Gardenias like an acid-based fertilizer so use Miracid or Miracle Gro. Wisteria needs full sun and a very sturdy support because it is a large, heavy vine reaching 30 feet or more. Prune after bloom, cutting the new growth back to three buds. This will encourage the development of new flowering wood. Apply ample water and feed by spreading a thick compost mulch around the root area. (Too much nitrogen fertilizer will produce vigorous top growth at the expense of blooms). Enjoy your garden!